Preparation and Evaluation of Gastro Retentive Floating Tablets of Atorvastatin Calcium

Abstract

This investigation describes the preparation and in vitro evaluation of gastro retentive floating tablets
of atorvastatin calcium. Two hydrophilic cellulose derivatives, Methocel K4M and Methocel K15M CR were used in
floating tablets as gel forming agents to control drug release. Sodium bicarbonate and citric acid were incorporated as
gas generating agents. The tablets prepared by direct compression technique were evaluated by various quality
parameters including weight variation, hardness and buoyancy studies. In vitro drug release was determined for eight
hours using USP XXII paddle-type dissolution apparatus in 0.1N HCl solution containing 1% sodium lauryl sulphate.
The release mechanisms were explored and explained with zero order, first order, Higuchi and Korsmeyer equations.
The release rates, extent and mechanisms, were found to be governed by polymer loading. It was also found that the
polymer content significantly affected the mean dissolution time, percentage of drug release, release rate constant and
diffusion exponent. Based on the dissolution data and floating time, formulation F-3 containing Methocel K4M and
F-9 containing Methocel K15M CR may be considered as the best formulation. So an effective floating tablet of
atorvastatin calcium can be prepared by using both the grades of HPMC.